Major Findings 



TABLE 1 - 1 Annual Production of Tundra Pond Communities 



Type of community 



Production 

 gC m yr 



Method of 

 measurement 



carbon-14 

 carbon-14 

 biomass changes 

 biomass changes 

 biomass changes 

 biomass changes 

 biomass changes 

 CO2 evolution in cores 

 CO2 exchange with 



atmosphere 

 biomass changes, lab 



growth rates 

 biomass changes, lab 



growth rates 



roots of the grasses and sedges enter the detritus food chain as there are no 

 grazers on the Hve plants. Most of the detritus is mineraHzed by bacteria 

 and fungi but some is consumed by chironomid larvae, the dominant 

 animals of the sediment. These larvae eat a few percent of the bacteria and 

 algae per day as do the microfauna of nematodes, harpacticoid copepods, 

 and protozoans. 



Flux of Carbon 



The measurement of the flux of carbon is a useful way to begin an 

 ecosystem study, as all the important elements can be identified. The 

 techniques we used for the carbon flux and standing stock are standard 

 ecological measurements such as '''C for the primary productivity of the 

 algae, biomass changes for rooted plants, CO 2 partial pressures by gas 

 analysis to obtain water-air exchange, laboratory respiration studies of 

 larger organisms, and acridine orange direct counts for the bacteria. The 

 only component of the biota not measured was the fungi. A single 

 measurement indicates that in sediments the mass of fungal hyphae is 

 about equal to the mass of bacteria. 



The rooted plants in the pond provide most of the input of organic 

 carbon (Figure 1-5, Table 1-1). They release dissolved organic carbon into 

 the water, release a large quantity of CO 2 via root respiration, and add 

 dead leaves, stems, and roots to the detrital pool. Once it reaches the 

 sediments, a leaf of Carex takes 4 years to decompose. One reason for this 

 rather long life-after-death is the lack of shredders in the pond ecosystem. 

 Another reason is the 9 months of cold storage each year (however, 

 freezing and thawing does mechanically damage the leaves). When 



